Introduction

Secure telecommunications is a subject which has been addressed extensively in the past; the same is true for the secure World Wide Web. An overview of this topic may be found in the paper by P. Lipp and V. Hassler [10]. Protocol realizations such as SHTTP [14] or SSLeay [13], an implementation of SSL [5], are examples of the prior art in this field.

Yet even in 1996 B. Fernandez noted in [3] that these works concentrated primarily on low level security ; these approaches do not address the multimedia or structural elements of the application documents. This is an area which has received scant attention in the past and on which this paper tries to shed some light.

From [3]:

``Hypertext systems encompass multimedia documents with hyperlinks connecting to other similar documents. Multimedia documents and their hyperlinks may contain a variety of media including audio, video, animation, graphics and text. Extensive research is going on about hypertext/multimedia systems as they are the upcoming platform for worldwide transfer of information. With this rapid growth in hypertext documents and WWW sites, their security is a top priority issue. Compared with other topics, this is a relatively neglected aspect. This is strange because the richness and variety of multimedia information provides with many opportunities to access unauthorized information. Most of the work until now has focused on methods to protect the information or authenticate the users using cryptographic measures. While these are certainly useful, they are too low level to control access based on logical properties of the document information.''

To overcome these deficiencies a security platform Plasma for multimedia telecommunications and applications has been designed and implemented for differentiating between media and structural components and using different cryptographic algorithms accordingly. For the purpose of demonstrating the functionality of Plasma, the World Wide Web was chosen. The reasons for this were that on one hand more and more transactions occur via the web, making the WWW one of the principal applications in electronic communications overall; on the other hand the World Wide Web constitutes a multimedia system as well as a hypertext system with components which can be distinguished by the structure of the application documents.

Plasma was a project within the RD-programme of Deutsche Telekom Berkom GmbH, which is a subsidiary of Deutsche Telekom AG. Deutsche Telekom has developed a product version of Plasma which is based on Deutsche Telekom's security technology as well as the results of the Plasma research project. Plasma is currently available for several operating systems. In this contribution all mentioning of Plasma refer to the Plasma research project and the Plasma prototype realized in this project.